While there are many makes and designs of machines for continuous freezing of soft desserts, most of them operate on a similar principle. A mixture of milk products, sugar, gelatin or similar thickener, flavors, coloring, nuts, fruits, syrups and sometimes eggs for both flavor and whipping ability is fed into a metal cylinder or mixing chamber around which a compressed gas is expanded, making the metal surface very cold. Ice crystals freeze to the surface and while yet quite small, they are scraped off by sharp blades revolving around the interior of the cylinder. Part of the scraping assembly is a beating arrangement that whips in air, thus increasing the volume of the mixture. The assembly moves the frozen dessert to the discharge mechanism as well.
Air incorporated into the mix is known as "overrun." While a regular ice cream may have 100% overrun, which means 50% of air by volume, a soft ice cream usually has 30-80% overrun, which means 20-40% of air by volume.
A wide variety of commercial extruders for soft frozen desserts exist, most of which are designed for use at the retail sales level to dispense soft frozen desserts, including frozen yogurt, into cones and dishes. Such dispensers can be found in U.S. Pat. Nos. 4,412,428; 4,707,997; 4,796,784; and 4,544,085, incorporated herein by reference and UK Patent application GB 2,234,556. The amount of dessert dispensed is generally dependent upon the length of time and degree of movement a lever or delivery tap is pushed. Such taps can be found in U.S. Pat. Nos. 3,868,050, 4,711,376 and EP 285,709 A1.
Especially for commercial production, but also desirable at the retail level, is the volumetric extrusion of food material. One approach to this is disclosed in U.S. Pat. No. 4,671,429. Volumetric injection of extruded food material is disclosed in U.S. Pat. Nos. 4,752,488 and 4,788071, incorporated herein by reference, both issued to Torshiko Hayashi. In U.S. Pat. No. 4,752,488, a plunger creates a vacuum sucking the material from a hopper into a discharge chamber using a 3-way valve, and then dispenses the material through a reciprocating injection nozzle. The length of the filling nozzle can be adjusted. U.S. Pat. No. 4,788,071 discloses a method for quantitatively extruding food materials having large chunks, by moving a piston through a cylindrical space in a hopper.
Pistons are used to aid in the extrusion of frozen desserts in a variety of ways. U.S. Pat. No. 4,580,905 discloses a piston which combines mixing and dispensing functions. UK Patent Application GB 2,172,541 discloses a plunger coordinated with an iris for forming geometrically shaped ice cream pieces.
A cooling tunnel consists of an insulated passage placed around the conveyor to let the product travel through it in a continuous flow. Cold gas is supplied to this passage to cool the product. To achieve maximum heat transfer from the gas to the product, a counterflow principle is used whereby air is introduced at the product exit of the tunnel and withdrawn at the product entrance of the tunnel so that the direction of the air flow is opposite to the direction of the food flow.
Conventional confection dispensing machines generally have one or more mix receptacles located in a bottom portion of the machine. Mix placed in the receptacle is pumped to a mixing chamber located behind the tap levers. The mixing chamber agitates and chills the mix into an extrudable frozen confection. Generally, the machine does not extrude the frozen confection until a desired viscosity and/or temperature has been achieved.
When the supply of mix is exhausted, additional frozen confection mix is supplied to the machine by an operator. After adding the mix, the operator waits for a period of time until the mixture has been beaten and cooled to an acceptable consistency and/or temperature. Upon reaching the proper characteristics, the frozen confection is dispensed from the machine as soft serve, or the like. Thus, after the supply of mix is exhausted, significant time elapses during which the operator obtains additional mix, accesses the mix receptacle, pours in the mix, and waits for the mix to obtain the desired consistency and/or temperature. This time does not include any period of time that the operator has not yet discovered that the supply of mix has been depleted.
In addition to machine down time, there are further drawbacks to adding additional mix to conventional frozen confection machines. The mix receptacle is typically located behind a door in a lower portion of the frozen confection dispensing machine. To add mix to the machine, the operator opens the door in the front of the dispensing machine and pours the frozen confection mix into the mix receptacle. Opening of the door results in temperature fluctuations in the interior of the machine as outside air enters. Such temperature fluctuations encourage the growth of unhealthy bacteria in or about the machine causing batches of mix to become contaminated and therefore unusable.
The open door also provides a passageway for undesirable air borne foreign objects or materials to enter the machine. Such objects and materials can be dispensed from the machine to an unsuspecting end user resulting in possible serious medical consequences.
Where one or more machines are utilized in an assembly line environment, the disadvantages described above can be magnified so that refilling the frozen confection dispensing machines becomes a significant cost of production. For a production line having several machines located adjacent to a conveyor belt, each machine must be periodically refilled with mix. As described above, for each machine that runs out of product, that machine must be taken off-line and refilled. More particularly, after an operator first notices that a machine is no longer dispensing product, the operator moves the machine away from the conveyor belt to open the front door. After the door is opened, the operator pours additional mix into the receptacle and closes the door. It will be appreciated that since the door is located in the bottom front of the machine, the task of continually refilling the machines can become an especially burdensome task. Also, repeated opening of the door allows dust and dirt to enter the machine and it puts a greater demand on the cooling system. After refilling the machine, the operator returns the machine to face the conveyor belt. The mix is then agitated and chilled in the mixing chamber for a period of time to allow the mix to reach a desired consistency, after which extrusion can commence.
Since each machine contributes to the assembly line, production is reduced or stopped for the time needed to refill each empty machine. Production line down time can be compounded if more than one machine must be refilled at any one time. Machine down time incurs other costs as well. For example, the operator is compensated regardless of production efficiency, non-conforming product is wasted, and product demand is unmet.
A frozen confection dispensing machine is desired that can extrude a predetermined amount of frozen confection while being refilled and is adaptable for assembly line operation.